Hi, I am building my first AllStar Node using HamVoip and I am following G5REV’s youtube tutorial. Yet I came up with a problem. The node is transmitting and hearing the initial IP address and callsign voice prompt on my HT. yet when I am about to transmit, the node is not receiving. I tried manually triggering the COS via putty on simpleusb/pressing K on settings, and connected it to a node 40894 for audio test. It is receiving! I checked the voltage on the COS pin where I connected it to the baofeng and initially I am reading about 1.75 volts when it is receiving then when I took some tweeking, it is no longer changing voltage when I transmit.
Is it possible that I the baofeng that I bought is defective or I fried it at some point? or is it just the COS voltage is too low to trigger the CM108 usb fob?
While not familure with the document you are working from…
As a test, I would remove the cos line from your URI .
Then check the voltage changes. If they are now present, you may have a short or something. It is possible by whatever the cause that you are sinking more current than the radio can give at that point.
Use of a resistor or a transistor buffer may be needed.
The easiest place to grab a active rx indicator voltage for cos on those radios is the led that shows active rx…
Could you point to the document you are working from ?
Hi, glad to hear from you OM Mike. Si I’ve been tinkering my setup after posting this topic. And it really turns out that I fried my bf888s. I found this out by opening my spare bf888s and its COS is working giving around 3v when receiving. I checked the first bf888s and saw that when I soldered it. the bare wire is exposed so when I screw the board back to the heatsink it is slightly touching it. So when I transmit, I somehow slowly killing the COS output by shorting it to the ground of the heatsink. Now I hooked it up to the new bf888s and it is working. Nice! …Well kind of. I am testing it on the audio test node and I could hear my self back. Yet I am having a problem now on the false triggering. PTT and COS are sometimes both detected on supermon. " COS and PTT are both detected (Full-duplex)" then Idle then a beep keys up.
Well, I know it’s against ham nature when I say,
Dont be cheap. Hi Hi
I would always suggest a buffer transistor when attaching to these low voltage radios.
You don’t have to stick it in the radio (save the room)
stick it on the URI side of the wire.
It gives a little isolation protection, and you just can’t say what some extra current draw may be doing to the rx. I’m not a engineer but I did stay at a holiday inn last week.
Just a case of safe rather than sorry.
2n2222’s and 3904’s and 3906’s are pretty cheap on ebay. I buy them by the 100.
Ham shack tools !
The issue you are having seems to be related to the threshold voltage which I do not know exactly what it is on your uri. But the transistor buffer would be the quick easy and cheap fix,
It takes very little current to trip the transistor and will satisfy your uri.
But you may have to invert the logic depending on how you do it.
Reading your last post a few more times, you may also have a issue with some transistor or other switching making noise in the rx ?
You might try adding some time to
rxondelay = 10 ;for starters. each# is 20ms I think
see if that helps the issue. (if i’m understanding what you said)
As mike said, adding switching transistors isn’t just a good idea, sometimes it’s necessary. People often get confused as to what is required to make most of the radio interfaces change states where COS (and CTCSS) is concerned.
The COS and CTCSS logic inputs on CM1XX based radio adapters were originally the volume-up and volume-down functions, actuated by manual (push button tactile) switches in a standard audio adapter (FOB). These inputs are internally pulled high, to 3.3 V, and have to be pulled low enough to become valid. As such the push-button switches made a good ground when depressed, as that’s what the other side of the switch was tied to - ground. Most AllStar radio adapters use protection diodes (BAT-43’s) that don’t allow voltage to be sent into the CM1XX chip. If voltage is allowed to be inputted to these pins, the chip is destroyed. So - with the diodes in place, it doesn’t matter what voltage is present on the COS or CTCSS hardware inputs, because voltage on these pins doesn’t make anything happen, and because of the protection diodes, doesn’t hurt anything if voltage is present. Pull-up resistors are totally unnecessary, because we need a ground to assert the condition. Any reference you see to “active high” or anything indicating the COS and CTCSS signals need to go high to become valid is technically incorrect.
Okay, so the CM108/119’s logic inputs are looking for a ground to be valid. This “active low” condition is required NO MATTER if the setting in the conf file is upright or inverted. So - the setting in the configuration file doesn’t change the fact that the adapter needs an active low to be valid and assert the condition. All this software setting does is change if the low condition exists when the radio is hearing a valid signal, or when it’s not. Using a DMM, you can read the voltage on the CM119 side of the BAT-43 diodes to see if the logic level is properly changing from approximately 3.3V to 0.0 (or a few tenths of a volt). If the voltage is not being pulled below 1V, and closer to 0V, it’s not going to work.
Not all radio logic signals are created equal. Some logic circuits can source current, but lack the ability to sink. Sometimes active high circuits (circuits that provide a voltage when the state becomes active) don’t have the ability to pull to ground very well. These circuits may not have the capability to pull the COS and CTCSS inputs low enough on the radio adapter to become valid/active. A pull-down resistor can help, but nothing beats a real active low circuit. A 2N2222 (or similar NPN transistor) with the emitter grounded usually works well.